Nuclear Cardiology (SPECT)

         

Nuclear Cardiology at the Cantonal Hospital of Olten

 

Last update: 24.12.2015

 

 

 

 

More informations

 

 

Nuclear Cardiology Update 07/2009

 

What is CardioSPECT?

 

Prognosis of MPS in relation to perfusion defect size and other scintigraphic markers

Kardiolvaskuläre Medizin April 2009

 

Diagnostic Accuracy of LHR and PDS to detect severe and extensive CAD

 

 

Kardiolab has performed exactly 8'270 SPECT Studies between Juli 1994 and December 2015 (using the single day rest-stress SestaMIBI Protocol) and eventually accompanying exercise-echocardiography, a somewhat unique performance in Switzerland.

SPECT (single photon emission computed tomography) is a cornerstone in diagnostic and prognostic testing in contemporary medicine. There is almost no other test, for which diagnostic and prognostic performance was tested as extensively in many several 10'000 of patients both for exercise as for pharmacological testing.

Despite beeing a test with high reported accuracy, the quality of SPECT myocardial perfusion studies are still dependent on the ability of the examiner.

 

I have performed now exactly 8'000 such studies. Where do we stand ? First of all, perfusion imaging using SPECT is reliable and reproducible at our institution. Normal perfusion has excellent prognostic impact. However, in a small subset of patients, severe coronary obstruction may be missed. How to circumvene this problem ? With Cardio-SPECT !

 

Our scientific drive has challenged these questions with a variety of published and ongoing studies. First, perfusion assessed by SPECT is a relative measure and therefore, severe coronary artery disease may be missed. Surrogate markers of myocardial performance are gated SPECT, stress induced lung uptake (Lung-heart-ratio, LHR), untriggered left ventricular volumes (VOL) and transient ischemic dilation ratios. For all these variables, Kardiolab has performed rather large studies that are under the process of publication and scientific evaluation.

 

However, that solves only a part of the problem. As an example, transient ischemic dilation may indicate severe obstructive coronary artery disease or simply subendocardial, prognostically benign, ischemia. How differentiate ?

 

Here comes a new modality into play. I would call it Cardio-SPECT, which means, that SPECT is extended by stress echocardiography. I have started this combination back in 1998 and performed in feasible patients more than 5'000 combined stress-echo and perfusion SPECT studies.

 

What may Cardio-SPECT add to SPECT ? First of all in subjects with increased TID, hyperkinetic left ventricular function is ruling out severe coronary artery disease, therefore, an invasive work up may be avoided. Further, cardiac abnormalities readily assessed by echocardiography, such as subaortic stenosis or exercise induced pulmonary hypertension may add substantial diagnostic information. In subjects with atrial fibrillation, where gated SPECT cannot be used, Cardio-SPECT adds indpendent and incremental prognostic information, since left ventricular ejection fraction is still the strongest prognostic factor in cardiology.

 

Cardio-SPECT, an almost unique feature of Kardiolab in the diagnostic and prognostic work up of patients referred for myocardial perfusion scintigrapyh, is therefore strongly recommended. Kardiolab uses currently VIVID-Q cardiac imaging with high diagnostic information in many patients. Of course, you may ask, why SPECT if Echo is normal. That's correct. But a the confidentiality of a normal SPECT, even in my hands, is higher than stress echo. If uncertainty exists with stress-echo, a normal perfusion scan is a highly reassuring finding. Why ? Exercise induced wall motion abnormalities such as tardokinesis are frequently unspecific for coronary artery disease.

 

Radiation Burden: we have adopted in 2015 the BAG specifications for Technetium Sesta MIBI radiation application in patients referred to our MPS imaging center.

 

Exercise Physiology

Does CMR provide the famous one-stop-shop? No!

Cardiovascular Magnetic Resonance (CMR) may detect coronary obstruction, previous myocardial infarction and a variety of cardiac problems during the same session using either dobutamine or adenosin as stressors. Assessing all potential problems asks patients to remain in the scanner for several hours. What might readily be seen in an echocardiogram takes many cuts and sequences with CMR and is about ten times more time consuming than echocardiography - besides the cost and the discomfort for the patients. The prevalence of diseases increases with age, as well as unspecific symptoms such as dyspnea as an equivalent for severe coronary artery disease, pulmonary hypertension of any cause or valvular disease. During the past ten years, there has been a growth in a fundamental misconcept in cardiology, e.g. that pharmacological stress testing is equally effective to exercise physiology. This has lead investigators to use and promote mainly vasodilator stress studies in CMR laboratories and for the detection of the functional significance of coronary stenoses using coronary CT or fractional flow reserve (FFR). Vasodilator Stress - a misconcept in modern cardiology

The problem with this stressor in a patient able to exercise - and far less is known about the effect of dobutamin stressing - is the problem of coronary steal, which leads to misleading results (false positive ischemia) in a given patient with symptoms and functionally working collaterals. Using exercise physiology, the risk of misclassification of a patients real life coronary ciculation appears much lower. Further, exercise physiology may provoke coronary spasms, which usually are not provokable by vasodilators. CardioSPECT is the real one-stop-shop

CardioSPECT was published in 2006 by Kardiolab and includes a comprehensive assessment of exertional symptoms such as angina or dyspnea using a dataset of objective measurements to assess the underlying disease that include

  • myocardial perfusion SPECT with the
  • addition of Lung-Heart-Ratio
  • Transient ischemic dilation ratio
  • Exercise Echocardiography with the addition of
  • peak pressure gradients over the triscupid valve
  • right ventricular function with 2D and TAPSE

Using this approach, a variety of diagnostic differentiation becomes clinically sizable. Especially the causes of exertional dyspnea can be further differentiated in an objective manner. One can differentiate between arterial and venous pulmonary hypertension, global myocardial ischemia or diastolic dysfunction. All together with the patients history and other data may give important hints to the clinician: does the patient need a coronary angiogram or rather an exercise right heart cath? Not to speak about the therapeutic implications that such differentiations may have not only on patients management but also on his well being and prognosis. Therefore, in the combination of two very well validated imaging modalities - exercise SPECT and echocardiography - all clinically important aspects can be evaluated rapidly, with relatively little patient dysconfort and with a much higher diagnostic information than what can be obtained from adenosin CMR, FFR or adenosin CT.

More informations